Method of making castor oil soap



Patented Mar. 2, 1937 i 2,0723% NETHOD 01F MAKING .CASTOR 01L SOAP Oncy lP. Puryear, Beacon, N. Y assignor to The Texas Company, New York, N. Y a corporation of Delaware No Drawing. Application May l, 1934, Serial No. 724,463

8 (Claims.

This invention relates to lubricants and particularly to lubricants containing a soluble castor oil ingredient.

An object of the invention is to produce an improved castor oil product which is soluble in mineral oil.

A further object of the invention is to form a castor oil soap which is soluble in mineral lubricating oils.

Another object of the invention is to provide a simple and practical method of preparing lubricants containing a soluble castor oil soap ingredient.

Another object of the invention is to produce an improved grease containing a soluble castor oil soap.

Castor oil is ordinarily insoluble in petroleum oils and several methods have been devised for rendering it soluble therein. The prior methods include distillation with or without the addition of a carrier oil whereby about d5% of oxygencontaining materials are removed. The resulting product, while soluble, is often thick and gummy and has an objectionable odor and color. Another method has consisted in using a solvent aid or blending agent which is mutually soluble in castor oil and mineral oils but these third ingredients are often undesirable.

Soluble metallic soaps of castor oil have also been made heretofore but such has been done by first producing a soluble castor oil product and then forming the metallic soap of the soluble product. The soaps made according to prior methods, however, have in general thedisadvantages of the soluble castor oil from which they are made.

I have found that an improved soluble castor. oil soap may be made easily and practically by saponiiying ordinary castor oil to form a soap no mixturewhich is normally insoluble in mineral oil and then heating this mixture to sumcient temperature to vaporize'the products which render the castor oil insoluble. tained is miscible with mineral oils and serves all as a convenient ingredient for incorporation into greases. If desired, the castor oil in a soluble form may be recovered by well known means from the soap to obtain a mineral oil-soluble castor 011 product.

In accordance with the invention, the castor oil to be treated is put into a suitable heating vessel, such as a grease kettle, and alkali slowly added with stirring. The castor oil is saponified and when it tends to become hard, heat is i applied. The castor oil soap product is melted The product so ob.-

Percent.

Castor oil 55.9 Mineral oil (300 viscosity at 100 F. Saybolt Universal) ..39.0

Caustic soda (43% solution) 5.1

The castor oil was charged to a grease kettle adapted to take off a vapor fraction. Stirring was started and aqueous caustic soda slowly added over a period of about two hours. The mixture was converted to a solid white soap. The mixture was heated and at about 400 F. melted. The temperaturewas raised to about 500 F. when vapors came ofi. The temperature was maintained at this point for about 3 hours and about 5% was removed as vapors. The temperature was then dropped to about 350 F. and the mineral oil gradually added, while stirring, over a period of about 5 hours. The temperature was dropped to around 170 F., a. small amount of water added to produce an. emulsion, and the greasedrawn from the kettle.

The product had a smooth texture and a yellow color. It tested as iolows:

Penetration -Q 298 Melting point, F 241 Soda soap per cent 21.8 Free neutral fat do"..- 37.9 llfineral oil do 41.4 Free alkali do... 0.22 Water do 0.50

The above example merely illustrates one grease within the scope of the invention. It is contemplated that in this type of greases the soap and oil content may vary within a wide range, say'from 10-50% of soap, and 50-90% of neutral oils. Also the castor oil may be partially saponified or substantially completelysaponified. However, I prefer to use sufllcient caustic to saponify 25-75% of'the castor oil in which case sufllcient excess castoroil is avail-' able to maintain the free alkali at a minimum. It will also be understood that other ingredients may be incorporated into the grease, such as other soaps and oils. The invention is also useful in the preparation of liquid lubricants and in lubricating compositions in which the castor oil ingredient is present only in a relatively small amount.

The lubricants made in accordance with the present invention have the advantages that they are relatively stable and maintain their body and consistency at high temperatures.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. The method of preparing an oil-soluble castor oil soap product, which comprises forming a mixture of castor oil and castor oil soap, said mixture being normally insoluble in mineral lubricating oils, heating the mixture to a temperature of around 500 F. and maintaining the temperature for suflicient time to vaporize a portion of the mixture in sufiicient amount to render the mixture soluble in mineral oil. 1

2. The method of preparing an oil-soluble castor oil soap, which comprises saponifying the castor oil with an alkali and heating the resultant soap to a temperature sufllciently high to efiect substantial dehydration, thereby forming a product normally insoluble in mineral lubricating oil, then further heating the soap to a temperature of around 500 F. and maintaining the latter temperature for suflicient time to distil from the dehydrated soap a fraction in sufiicient quantity to render the soap soluble in mineral lubricating oil. 0 g

3. The method of preparing an oil-soluble castor oil soap product, which comprises forming a castor oil soap mixture, normally insoluble in mineral lubricating oil, by reacting castor oil with suflicient alkali to effect saponification of the major portion of the castor oil and heating the mixture to a temperature sufliciently' high to effect dehydration thereof, then further heating the mixture to a temperature of upwards of 500 F., and maintaining the latter temperature for suilicient time to distil materials which render said mixtureinsoluble in mineral oil, whereby an undistilled soap product soluble in mineral lubricating oil is formed.

ONEY -P. PURYEAR. 

